function selet(selector){
	var result = document.querySelectorAll(selector);
	if(result.length === 1){
		return result[0]
	}
	return result;
}
function bindEvent(nodeList,eventType,fn){
	for(var i = 0; i < nodeList.length;i++){
		nodeList[i][eventType] = fn
	}
}
function getRandomColor(){
	var arr = ["0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f"];
	var result = "#";
	for(var i = 0; i < 6;i++){
		var index = Math.floor(Math.random() * 16)
		result = result + arr[index];
	}
	return result;
}